[FileCheck] Fix redundant diagnostics due to numeric errors

[jdenny]

Summary

Fixed substitution printing not to produce an empty diagnostic for
errors handled elsewhere.

[jdenny]

Rebased for changes to D98086.

[thopre]

LGTM, thanks!

[jdenny]

Rebased for contextual changes from D98086.

llvm/lib/FileCheck/FileCheck.cpp

for (const auto &Substitution : Substitutions) {
             [&](const UndefVarError &E) {
               if (!UndefSeen) {
                 OS << "uses undefined variable(s):";
                 UndefSeen = true;
               }
               OS << " ";
               E.log(OS);
             });
+        if (!OS.tell())
+          continue;
       } else {
         // Substitution succeeded. Print substituted value.
         OS << "with \"";
         OS.write_escaped(Substitution->getFromString()) << "\" equal to \"";
         OS.write_escaped(*MatchedValue) << "\"";
       }
 
       // We report only the start of the match/search range to suggest we are

llvm/test/FileCheck/match-time-error-propagation/invalid-excluded-pattern.txt

 ; Check handling of match-time diagnostics for invalid patterns (e.g.,
 ; substitution overflow) in the case of excluded patterns (e.g., CHECK-NOT).
 ;
 ; At one time, FileCheck's exit status was zero for this case.  Moreover, it
 ; printed the error diagnostic only if -vv was specified and input dumps were
 ; disabled.  Test every combination as the logic is hard to get right.
-;
-; FIXME: We shouldn't have: (1) the blank note at the end of the trace, and
-; (2) the redundant error in the middle of the dump.  These will be fixed in a
-; subsequent patch.
 
 RUN: echo > %t.chk \
 RUN:      'CHECK-NOT: [[#0x8000000000000000+0x8000000000000000]] [[UNDEFVAR]]'
 RUN: echo > %t.in '10000000000000000'
 
      ERR-NOT:{{.}}
       ERR-VV:{{.*}}: remark: implicit EOF: expected string found in input
  ERR-VV-NEXT:CHECK-NOT: {{.*}}
  ERR-VV-NEXT:{{ *}}^
  ERR-VV-NEXT:{{.*}}: note: found here
 ERR-VV-EMPTY:
  ERR-VV-NEXT:^
      ERR-NOT:{{.}}
          ERR:{{.*}}: error: unable to substitute variable or numeric expression: overflow error
     ERR-NEXT:CHECK-NOT: {{.*}}
     ERR-NEXT:{{ *}}^
-    ERR-NEXT:{{.*}}: note: 
-    ERR-NEXT:10000000000000000
-    ERR-NEXT:^
     ERR-NEXT:<stdin>:1:1: note: uses undefined variable(s): "UNDEFVAR"
     ERR-NEXT:10000000000000000
     ERR-NEXT:^
      ERR-NOT:{{error|note|remark}}:
 
         DUMP:<<<<<<
    DUMP-NEXT:         1: 10000000000000000 
    DUMP-NEXT:not:1'0     X~~~~~~~~~~~~~~~~~ error: match failed for invalid pattern
    DUMP-NEXT:not:1'1                        unable to substitute variable or numeric expression: overflow error
-   DUMP-NEXT:not:1'2     X                  error: match failed for invalid pattern
-   DUMP-NEXT:not:1'3                        uses undefined variable(s): "UNDEFVAR"
+   DUMP-NEXT:not:1'2                        uses undefined variable(s): "UNDEFVAR"
 DUMP-VV-NEXT:         2: 
 DUMP-VV-NEXT:eof:1       ^
    DUMP-NEXT:>>>>>>
 
 ;--------------------------------------------------
 ; Check -dump-input=never cases.
 ;--------------------------------------------------
 

llvm/test/FileCheck/match-time-error-propagation/invalid-expected-pattern.txt

 ; Check handling of match-time diagnostics for invalid patterns (e.g.,
 ; substitution overflow) in the case of expected patterns (e.g., CHECK).
-;
-; FIXME: We shouldn't have: (1) the blank note at the end of the trace, and
-; (2) the redundant error in the middle of the dump.  These will be fixed in a
-; subsequent patch.
 
 RUN: echo > %t.chk \
 RUN:      'CHECK: [[#0x8000000000000000+0x8000000000000000]] [[UNDEFVAR]]'
 RUN: echo > %t.in '10000000000000000'
 
   ERR-NOT:{{.}}
       ERR:{{.*}}: error: unable to substitute variable or numeric expression: overflow error
  ERR-NEXT:CHECK: {{.*}}
  ERR-NEXT:{{ *}}^
- ERR-NEXT:{{.*}}: note: 
- ERR-NEXT:10000000000000000
- ERR-NEXT:^
  ERR-NEXT:<stdin>:1:1: note: uses undefined variable(s): "UNDEFVAR"
  ERR-NEXT:10000000000000000
  ERR-NEXT:^
   ERR-NOT:{{error|note|remark}}:
 
      DUMP:<<<<<<
 DUMP-NEXT:           1: 10000000000000000 
 DUMP-NEXT:check:1'0     X~~~~~~~~~~~~~~~~~ error: match failed for invalid pattern
 DUMP-NEXT:check:1'1                        unable to substitute variable or numeric expression: overflow error
-DUMP-NEXT:check:1'2     X                  error: match failed for invalid pattern
-DUMP-NEXT:check:1'3                        uses undefined variable(s): "UNDEFVAR"
+DUMP-NEXT:check:1'2                        uses undefined variable(s): "UNDEFVAR"
 DUMP-NEXT:>>>>>>
 
 ;--------------------------------------------------
 ; Check -dump-input=never cases.
 ;--------------------------------------------------
 
 RUN: %ProtectFileCheckOutput \
 RUN: not FileCheck -dump-input=never %t.chk < %t.in 2>&1 \